Reagents and Processes. 389 



obtainable in this country from dealers in microscope supplies. The 

 stains are made as follows : — 



1. A saturated solution of safranin in 95 % alcohol, diluted with an 

 equal bulk of distilled water. 



2. A saturated solution of gentian violet in distilled water. 



3. A saturated solution of orange G in distilled water, diluted with 

 5 times its bulk of distilled water. 



The safranin and gentian violet should be kept ready for use in 

 covered tumblers or Stender dishes, and the orange in a drop bottle. 

 In addition to the stains there should be conveniently at hand — 



4. A drop bottle containing absolute alcohol. 



5. A drop bottle containing clove oil. 



6. A tumbler of xylene. 



7. A tumbler of 95 % alcohol acidulated with i drop of concentrated 

 hydrochloric acid. 



Proceed with the staining as follows : — 



1. Set the slide upright in the dish of safranin for a few hours 

 or over night. (The paraffin having been dissolved away in xylene, 

 and the latter having been rinsed off in a dish of 95 % alcohol.) 



2. Rinse the slide quickly in water and place it in the dish of acidu- 

 lated alcohol (No. 7 above) until the safranin ceases to come away in 

 clouds. The sections should appear almost decolorized. 



3. Place the slide in the dish of gentian violet for 10 minutes. 



4. Rinse off the gentian violet quickly \a ith water and flood the sec- 

 tions with orange G from the drop bottle for 4 seconds. 



5. Rinse off the orange with water, and thoroughly dehydrate by 

 holding the slide slanting, sections upward, and dropping absolute alco- 

 hol over the sections from the drop bottle. 



6. Set the slide in a horizontal position and drop clove oil from tho 

 drop bottle over the sections. The preparation should now be watched 

 under low power of the microscope, and when the gentian violet has lost 

 its too great intensity and has a transparent quality, drain off the clove 

 oil and set the slide in the dish of xylene and let it remain there until 

 ready to seal the mount in balsam. If the sections have been success- 

 fully stained, the c\toplasni will be stained from gray to orange, the 

 resting nucleus violet, the nucleolus red. In the dividing nucleus the 

 chromosomes will be red and the spindle fibers violet. Cutinized mem- 

 branes will be red, lignified membranes blue, and cellulose membranes 

 will be almost colorless. 



